On a daily basis, pathologists examine the fundamental basis of human diseases using morphologic, immunologic, and molecular techniques. Cystic fibrosis (CF), as a clinically heterogeneous disease, exemplifies the complex challenges of genetic diseases for the pathologist who attempts to explain the mechanisms of disease and provide rationale for clinical management. This review includes an overview of CF and a discussion of pathophysiologic features and practical components of clinical and anatomic pathology, and concludes with a review of molecular diagnostics.